In a color imaging device such as a color digital camera, a color separation unit for separating light from a light source into primary colors is required. Color separation units which are based on the well known Bayer filter (described in commonly-assigned U.S. Pat. No. 3,971,065) are widely used in the industry. The Bayer color filter array suggests arranging R, G, B color filters on a square grid of photo sensors. This particular arrangement of color filters is used in most single-chip digital image sensors in digital cameras, camcorders, and scanners to create a color image. The Bayer arrangement of color filters on an image sensor array is two-by-two cell contains two green, one blue, and one red filter. This filter is often called RGBG filter, representing the color components included in each cell. There are twice as many green filters as red or blue ones, exploiting the human eye's higher sensitivity to green light.
The raw output data acquired by a Bayer filter is often called a Bayer pattern image. Since each pixel is filtered to record only one of three colors, the data from each pixel cannot filly determine color on its own, all four RGBG elements must be considered. To obtain a full-color image, various algorithms are employed, often called dernosaic algorithms. Those algorithms are used to interpolate a set of complete red, green, and blue values for each pixel, they require various amounts of computing power resulting in varying-quality final images. This can be done in-camera or in an attached computer, producing a JPEG, TIFF image format or raw data directly acquired from the sensor.
When imaging an object on a Bayer array configuration, proximal segments of the image are sensed by different sensors. The color separation per pixel, therefore, is not completely accurate and segmented. When presenting the sensed image, one usually relies on the averaging nature of the human visual perception.
U.S. Pat. No. 7,138,663 places a micro lens over a triplet of photoreceptors. Specific wavelengths of light are separated and passed to specific photoreceptors designated to record red, green, and blue wavelengths. Light separation is achieved with set dichroic mirrors. This system emulates three CCD imaging systems by using a single array. Image quality is theoretically improved due to the usage of much smaller gaps between photoreceptors assigned to a specific wavelength. Micro lenses are also used in order to collect all pertinent wavelengths components and reduce possible light loss.